Estimation of Extreme Value and Duration of Storm Surge in Bays by Using Stochastic Typhoon Model

In Japan many storm surge defense facilities have been constructed for the design tidal level taking account of the storm surge due to a standard typhoon based on the Typhoon Vera in 1959. Yet the tidal level over the design one may appear in small probability. This study, therefore, estimated the extreme storm surge with a return period of 10 to 1, 000 years in major bays in Japan on the Pacific Ocean, by using a stochastic typhoon model. The result shows that the return period of the current design tidal level in three major bays is several hundred years or more under the current climate but it may change due to the variation of typhoon appearance characteristics under Global warming. The duration of the peak on the storm surge and tidal level variation with time is short in the majority of typhoons with a large storm surge.